Heat exchanger with expansible tube seal



June 13, 1967 R. 'r. DIVERS 3,324,941

HEAT EXCHANGER WITH EXPANSIBLE TUBE SEAL I 7 Filed Jan. 2, 1964 2Sheets-Sheet 1 O00 O00 O00 000 FIG. 2 T2 24 INVENTOR. RAYMOND T. DIVERS.

ATTORNEY.

June 13, 1967 R. T. DIVERS 3,324,941

HEAT EXCHANGER WITH EXFANSIBIJE TUBE SEAL Filed Jan. 2, 1964 2Sheets-Sheet 2 ,22 B 3 {C 9s INVENTOR.

RAYMOND T. DIVERS.

ATTORNEY.

United States Patent 3,324,941 HEAT EXCHANGER WITH EXPANSIBLE TUBE SEALRaymond T. Divers, Carniilus, N.Y., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Deiaware Filed .ian. 2, 64. Ser. No.335,247 11 Claims. (Ci. 165-173) This invention relates to heat exchangeapparatus, and more particularly to a heat exchanger for use inrefrigeration systems.

Heat exchangers may be thought of as devices for bringing primary heatexchange medium into heat exchange relationship with secondary heatexchange medium. A typical heat exchanger includes a plurality oflongitudinally disposed heat exchanger tubes in a housing. In a heatexchanger of this type the area surrounding the exterior surfaces of theplural heat exchanger tubes may be in cornmunication with the primaryheat exchange medium while the area bounded by the interior surfaces ofthe heat exchanger tubes communicates with the secondary heat exchangemedium. By this construction the plural heat exchanger tubes serve asthe intermediary for bringing primary heat exchange medium into heatexchange relationship with the secondary heat exchange medium.

The efiicacy of a heat exchanger requires that the primary and secondaryheat exchange mediums be isolated one from the other. Since the pluralheat exchanger tubes constitute the sole bridge between primary andsecondary heat exchange mediums the seal between primary and secondaryheat exchange mediums at each of the plural heat exchanger tubes is ofcritical importance.

Where heat exchangers of the type described are disposed in positionsother than vertical, the heat exchanger tubes tend to sag. Tube sag mayplace an excessive strain on the seal between primary and secondary heatexchange mediums at each of the plural heat exchanger tubes withpossible impairment or rupture thereof. Additionally, the amount of sagof each of the plural heat exchanger tubes may vary, destroying thedesign spacing between each of the tubes and bringing tubes into contactwith one another. The flow of first and second heat exchange mediumsthrough the heat exchanger may induce the heat exchanger tubes tovibrate causing contacting or closely adjacent tubes to strike oneanother.

To obviate sag in heat exchanger tubes, additional supports, commonlyknown as tube support sheets, may be placed at selected intervals in theheat exchanger housing. Each of the tube support sheets has a pluralityof spaced tube receiving openings therein through which the heatexchanger tubes pass. The surrounding tube support sheet structure isrelied upon to limit movement of the tube in a radial direction andmaintain selected spacing between tubes.

In constructions where tube support sheets are utilized, it may beappreciated that the most effective support structure for maintainingthe heat exchanger tubes in predetermined spaced relation relative tothe heat exchanger housing and to each other is a support sheet havingtube receiving openings dimensioned approximately equal to or slightlyless than the outer dimension of the heat exchanger tubes. By thisconstruction each heat exchanger tube is rigidly positioned againstmovement in a radial direction at the tube support sheet. However,assembly of the heat exchanger by the expedient of moving the pluralheat exchanger tubes axially through openings in the support sheet orsheets is then impossible or extemely difficult. To permit the axialmovement of the heat exchanger tubes for ready assembly of the heatexchanger, tube support is compromised by making the tube support sheetopenings larger than the outer dimension of the exchange tubes. Thiscompromise arrangement provides a degree of support for each heatexchanger tube, and at the same assign ice time permits movement of theheat exchanger tubes through the support sheets during assembly anddisassembly of the heat exchanger. It does not, however, support theheat exchanger tubes tightly enough to eliminate sag of tubes betweensupports, and tube vibration.

To more effectively support the heat exchanger tubes, each heatexchanger tube may be expanded into contact with each of the tubesupport sheets. This construction permits the use of support sheetopenings with a dimension greater than the outer dimension of the heatexchanger tubes whereby assembly of the heat exchanger tubes isfacilitated and at the same time results in a high degree of tubesupport through the subsequent expansion of each tube into tightengagement with the support sheet. However, this construction isexpensive, time-consuming and often impractical. Where heat exchangershave a substantial axial length with a great number of relatively smalldiameter heat exchanger tubes and plural spaced support sheets, themagnitude of the problem facing the assembler in accurately locating andexpanding that portion only of each heat exchanger tube opposite each ofthe tube support sheets through which the tube passes may be readilyappreciated.

Conventional tube support sheets are normally formed from metal, usuallysteel. Contact between the steel support sheet and the outer surface ofthe heat exchanger tubes which are normally copper may result ingalvanic erosion. This may be enhanced by the particular heat exchangefiuid utilized in the system and by any tube vibration. Where the tubesupport sheet is formed from the same metallic material as the heatexchanger tubes, erosion induced by vibration of the heat exchangertubes may occur. To obviate tube erosion, each heat exchanger tubeshould preferably tightly engage the support sheet surface defining thetube receiving opening. However, as noted heretofore, the knowntechnique of expanding each tube into tight engagement with each of thetube sheets through which the tube passes is often impractical andalways expensive.

It is a principal object of the present invention to provide a new andimproved apparatus for maintaining heat exchanger tubes in predeterminedspaced relationship relative to one another and to the heat exchanger.

It is an additional object of this invention to provide a unique supportapparatus for heat exchanger tubes enabling the heat exchanger tubes tobe moved through openings in the support apparatus during assembly ofthe heat exchanger, the support apparatus being operable during heatexchanger use to tightly grip each heat exchanger tube to preventmovement thereof.

It is a further object of the present invention to provide a novel tubesupport sheet construction operable to tightly grasp the outerperipheral surface of heat exchanger tubes when exposed to heat exchangemedium.

it is an object of the present invention to provide a new and improvedmethod of making tube support sheets for heat exchanger apparatus.

It is a further object of the present invention to provide a new andimproved tube support sheet structure.

This invention relates to a structure for supporting heat exchangertubes in predetermined spaced relationship one to another, thecombination comprising first and second members having plural axiallyaligned openings therein, each pair of openings being adapted to receivea heat exchanger tube therethrough, and expansible means tightly heldbetween the first and second members at each of the tube openingsoperable upon exposure to heat exchange medium to expand into contactwith the heat exchanger tubes to secure the heat exchanger tubes to thefirst and second members.

This invention further relates to the method of forming a tube supportsheet for use in a heat exchanger having a plurality of spaced heatexchanger tubes therein, the steps which consist in placing ring-likeexpansible elements on a first tube support sheet part having aplurality of tube receiving openings therethrough opposite to andcoaxial with each of the tube receiving openings, disposing a secondtube support sheet part having a like number of similarly spaced tubereceiving openings therein oppos'te the first tube support sheet part onthe expansible e1..- ments with the tube receiving openings thereofcoaxial therewith, and bonding the first and second tube support sheetparts together to form a unitary tube support sheet.

Other objects will be apparent from the ensuing description and drawingsin which:

FIGURE 1 illustrates schematically a refrigeration system incorporatingthe present invention;

FIGURE 2 is a cross sectional view taken along lines 11-11 of FIGURE 1showing the tube support sheet;

FIGURE 3 is an enlarged fragmentary cross sectional through the tubesupport sheet shown in FIGURE 2 illustrating the expansi-ble tubegripping elements in expanded condition; and

FIGURE 4 is a view of an apparatus for fabricating tube support sheets.

Referring particularly to FIGURE 1 of the drawings, there is shown arefrigeration system embodying the heat exchanger tube support structureof the present invention. The refrigeration system includes a compressor12 having a suitable drive motor 14. Compressor 12 may be of anysuitable type, for example, centrifugal, rotary or reciprocating; ifdesired, compressor 12 may be housed with motor 14 to form a hermeticunit. It is understood that the present invention may be embodied inabsorption type refrigeration systems.

Compressor 12 compresses vaporous primary heat exchange medium orrefrigerant flowing through line 3 from the heat exchanger 2, acting asan evaporator. The compressed gaseous refrigerant is discharged throughline 11 into heat exchanger 20, acting as a condenser. Gaseousrefrigerant entering heat exchanger is liquefied through heat transferwith a secondary heat exchange medium, for example, water circulatingthrough the heat exchanger tubes 22. Liquid refrigerant from heatexchanger 20 passes through line 24 and suitable expansion means 26,

for example, a thermal expansion valve, through line 36 to the heatexchanger 2. Expansion means 26 provides the requisite pressure dropbetween the heat exchangers during system operation. Liquid refrigerantin heat exchanger 2 is vaporized through heat transfer with the media tobe cooled or chilled, for example, water circulating in the heatexchanger coils thereof.

Heat exchanger 20 comprises a generally cylindrical shell or housing 40with opposite end members or tube sheets 42, 43 sealingly attachedthereto to define cylindrical compartment 41. Tube sheets 42, 43 supportplural heat exchanger coils or tubes 22 passing through compart ment 41.A pair of headers 45, 46 are sealingly attached to tube sheets 42, 43respectively and define therewith end compartments 47, 48. Compartment47 is separated by member 50 into inlet and discharge chambers 52, 54respectively in communication with suitable heat transfer medium.

Tube sheets 42, 43 are each provided with an equal number of spacedopenings 60, 61 therethrough, each of the openings 6%) in tube sheet 42being in axial alignment with a corresponding opening 61 in the oppositetube sheet 43. The terminal ends of each heat exchanger tube 22 passthrough a pair of axially aligned openings 60, 61. Each terminal end ofthe heat exchanger tubes 22 may be expanded by suitable means (notshown) into tight engagement with the inner surface of the tube sheet 42or 43 defining the openings 60, 61 respectively to tightly sealcompartment 41 from the opposite end compartments 47, 48. Heat exchangertubes 22 may be grouped at 21, 23 into what are commonly known as tubebundles. Tube bundles 21, 23 communicate inlet and discharge cham- .4bers 52, 54 of compartment 47 with the compartment 48. Refrigerant lines11 and 24 communicate the heat exchanger compartment 41 with the systemcompressor 12 and expansion means 26 respectively.

During operation of the refrigeration system, cooling medium fromconduit 56 flows through inlet chamber 52 and heat exchanger tube bundle21 into compartment 48, and from compartment 48 through heat exchangertube bundle 23 and outlet chamber 54 into discharge conduit 57. Gaseousrefrigerant from the compressor 12 passes through line 11 intocompartment 41 of the heat exchanger 20. Liquid refrigerant incompartment 41 flows through line 24 and expansion means 26 to heatexchanger 2.

Referring to FIGURES l and 2 of the drawings, one or more tube supportsheets or baffies 70 are shown. Sheets 70 may be formed with paireddiametrically opposite arcuate sides 71 and planar sides 72respectively. Arcuate sides 71, having a radius substantially equal tothe radius of cylindrical heat exchanger shell 40, abut the innersurface of shell 46.

In constructions where it is intended that tube support sheets 70additionally function as baffies to route the flow of refrigerantthrough heat exchanger compartment 41, tube support sheet 7% may beformed with an arcuate side terminating in a single planar side. Thearcuate side, at a radius substantially equal to the radius ofcylindrical heat exchanger shell 40, abuts the inner surface of theshell 40.

A plurality of openings 74 having an inner dimension slightly greaterthan the outer dimension of the heat exchanger tubes 22 is provided ineach tube support sheet 70. Each of the openings 74 is disposed in axialalignment with a corresponding pair of openings 60, 61 in tube sheets42, 43 respectively. Tube support sheet or sheets 7 0 are located withincylindrical heat exchanger compartment 41 in predetermined spacedrelationship to tube sheets 42, 43. Preferably, tube support sheet orsheets 70 are fixedly secured to the inner surface of shell 40 bysuitable means (not shown). The coaxial relationship between each of theplural tube receiving openings in the support sheet 71 and a pair oftube receiving openings in support sheets 42, 43 establishes asubstantially straightline path for the heat exchanger tubes.

Use of supporting structure of the type described heretofore havingopenings therein for receiving heat exchanger tubes presents twodiametrically opposite problems. In order to assemble the heatexchanger, and to per mit removal of one or more heat exchanger tubesfor repair or replacement, the tube openings in the support sheet orsheets must have a dimension greater than the outer dimension of theheat exchanger tubes. By this means relative movement between the tubesand the support sheets, necessary during assembly of the heat exchanger,may be effected. Efiicient tube support, however, decrees that thesupport sheet closely surround, and preferably tightly grip, the heatexchanger tube. It is appreciated therefore that if the dimension of thesupport sheet opening too closely approximates the outer dimension ofthe heat exchanger tube, tube support may be realized at the expense ofvery difficult, or impossible, movement of the heat exchanger tubesthrough the support sheet openings. If the dimension of the supportsheet openings be sufiiciently great thereby permitting ready insertion,and withdrawal, of the heat exchanger tubes, excessive tube vibration,and tube sag between adjacent supports may occur.

Applicants novel ararngement, hereinafter described, provides a tubesupport sheet with tube receiving openings therein large enough topermit ready movement of the heat exchanger tubes therethrough duringassembly or disassembly of the heat exchanger, the tube support sheetbeing operable to tightly grip the heat exchanger tubes therein duringheat exchanger use.

In FIGURE 3 of the drawings, an enlarged view of applicants novel heatexchanger tube support sheet is therein shown. Tube support sheet orbaffle 70 is comprised of a relatively rigid member having a pluralityof spaced tube receiving openings or passages 74 therethrough. A portionof each of the openings 74 is comprised of a material adapted onexposure to the system refrigerant to expand or swell radially inwardinto abutting engagement with the heat exchanger tube therein as will beparticularly explained hereinafter. It is understood that the size,orientation, and number of tube openings 74- bear a direct relationshipto the size, orientation, and number of heat exchanger tubes to besupported. Preferably, openings or passages 74 have an inner dimensionprior to exposure of the tube sheet 70 to the system heat exchangemedium slightly greater than the outer dimension of the heat exchangertubes therein.

Tube support sheet 70 includes a pair of sheet-like parts 80, 82 eachprovided with a plurality of axially aligned open-ended extensions orprotrusions 84, 85 respectively. Expansible members 90 are positionedbetween parts 80, 82 respectively opposite each of the protrusions 84,85. Parts 80, 82, having expansible members 90 therebetween, arepreferably fastened together to form a unitary structure by a suitableadhesive or bonding material 104. Expansible members 90 are eachprovided with an opening 95 therethrough coaxial with and having adimension, before expansion of member 90, substantially equal to thedimension of the openings defined by protrusions 84, 85 respectively.Each pair of axially aligned open-ended protrusions 84, 85, having anexpansible member 0 disposed therebetween with opening 05 therethroughcooperate to form each of the tube receiving openings or passages 74. Asnoted heretofore, the dimension of tube receiving openings or passages74 prior to exposure of tube sheet 70 to the system refrigerant ispreferably slighty greater than the outer dimension of the heatexchanger tubes.

Expansible members 90 are formed from a suitable material adapted toswell or expand on exposure to the system refrigerant. Preferably,expansible members 90 each comprise a ring-like element having agenerally T- shape when viewed in cross section with oppositecircumferential locking surfaces 92, 93. Each expansible member 90 isheld or trapped between sheet-like parts 80, 82 through engagement oflocking surfaces 92, 93 thereof with the terminal areas of protrusions84, 85 respectively. By this construction each of the ring-likeexpansible members 90 is held in coaxial relationship with itsassociated protrusions 84, S5 to form an uninterrupted tube receivingopening or passage 74. While expansible members 90 are disclosed assubstantially ring-shaped having a crosssectional form resembling a T,other suitable shapes and/ or cross-sectional configurations thereformay be conteniplated.

Sheet-like parts 80, 82 with expansible members 90 therebetween define aspace which is substantially filled by a suitable relatively rigidmaterial 104 adapted to channel or funnel the expansion or swelling ofmembers 90, when exposed to the system refrigerant, radially inward intotight engagement with the outer peripheral portion of the heat exchangertubes. In a preferred embodiment of the invention, filler material 104also serves to fasten or bond sheet-like parts 80, 82 together withexpansible members 90 trapped between each pair of protrusions 84, 85 toform a unitary tube support sheet 70. A preferred filler material forbonding sheet-like parts 80, 82 together comprises a suitablethermosetting resin. Other suitable means for fastening or otherwisesecuring sheet-like parts 80, 82 together may be contemplated.

Sheet-like parts 80, 82 are formed from a suitable rigid material suchas metal, thermoplastic sheet stock, or thermosetting resin. Where parts80, 82 are formed from a thermosetting resin, suitable reinforcing meanssuch as metallic wire or thread, glass fiber thread, or chopped andrandomly oriented glass fiber particles may he formed integrallytherewith to enhance the rigidity of parts 80, 82. Parts 80, 82 arepreferably curved or bevelled at 83 to minimize chipping of the supportsheet 70 during insertion of the heat exchanger tubes therethrough.

As noted heretofore, expansible members 90 are comprised of a suitableelastomeric material adapted when exposed to the system refrigerant toswell or expand. A composition adapted to expand in the presence ofmonofluorotrichloromethane (CCl F), commonly known as refrigerant R-ll,is shown in the following example (in parts by weight):

2-chloro-1,3-butadiene 100 Stearic acid 0.5 Magnesium oxide 2 Carbonblack Zinc oxide 5 Z-mercaptoimidazoline 0.5

An example of a composition adapted to swell when exposed to a lithiumbromide (LiBr) solution, useful in absorption refrigeration systems, isas follows (in parts by weight):

In assembly of heat exchanger 20, tube support sheets or baffies 70 maybe fixedly positioned in compartment 41 by suitable means (not shown)with tube openings 74 therein in axial alignment with respective pairsof tube sheet openings 60, 61. Tube sheet openings 60, 61 and tubesupport sheet openings 74 preferably have a dimension slightly greaterthan the outer dimension of the heat exchanger tubes 22 wherebypositioning of the heat exchanger tubes 22 in openings 60, 61 and 74 isfacilitated.

Each of the heat exchanger tubes 22 is passed through a tube sheetopening 60 or 61 through each of the tube support sheet openings '74axially aligned therewith into the opposite tube sheet opening 60 or 61.The end portions of each of the heat exchanger tubes 22 may bethereafter expanded by suitable means (not shown) into tight engagementwith that part of tube sheets 42, 43 defining openings 60, 61respectively. On exposure to the system refrigerant, for example, whenthe system is charged with refrigerant, expansible members in tubesupport sheets 70 expand or swell to tightly grip that portion of theouter periphery of the heat exchanger tube 22 opposite thereto. As notedheretofore, the closely surrounding relatively rigid filler or bondingmaterial 104 channels expansion of each of the members 90 radiallyinward. By this arrangement, each heat exchanger tube is securely heldagainst movement relative to the tube support sheet.

Subsequent purging of refrigerant from the system causes expansiblemembers 90 to contract thereby freeing the heat exchanger tubes formovement relative to the tube support sheets. Disengagement of heatexchanger tube end portions from tube sheets 42, 43 permits withdrawalof the tube from the heat exchanger.

While applicants novel tube support structure is described in connectionwith the system heat exchanger 20, it is appreciated that heat exchanger2 may be similarly constructed.

Referring particularly to FIGURE 4 of the drawings, applicants noveltube support sheet may be formed by placing one of the paired sheet-likeparts 80 in assembly fixture with open-ended protrusions 84 thereoffacing outwardly. An expansible member 90 may be then placed on each ofthe protrusions 84. Locking surfaces 92 of member 90 fit over the endsof protrusion 84 to hold expansible members 90 on each of theprotrusions 84 with opening 95 therethrough coaxial with the openingdefined by the protrusion 94. Sheet-like part 82 may be then placed infixture 100 opposite part 80 by inserting the ends of protrusions 85 ina corresponding locking surface 93 of expansible members 90 whereby eachof the openings defined by protrusions 85 is coaxial with an associatedopening defined by protrusions 84 of sheet-like part 80.

The assembly may be held by suitable fastening means 108 in fixture 180.Fixture 101) may be provided with a gate 102 at the base thereof adaptedto communicate with the space defined by sheet-like parts 80, 82 and theouter surfaces of expansible members 90 trapped therebetween with asource of filler or bonding material, preferably thermosetting resin inthe liquid state. Riser 106 is provided at the top of fixture 100 topermit the egress of air from the space. Additionally, riser 106 servesto indicate complete filling of the space between parts 80, 82 andmembers 90. On the completion of the filling cycle as indicated by thepresence of thermosetting resin in riser 106, the flow of liquid resinis interrupted. The liquid resin in the space between parts 80, 82 andmembers 90 may be thereafter cured. At the completion of the curingcycle, the assembled tube support sheet 70 is removed from fixture 100.

If desired, the thermosetting resin injected into the space betweenparts 80, 82 and members 90 may be in the form of a froth adapted topolymerize into a rigid cellular structure upon curing. Alternately, thethermosetting resin may comprise a suitable liquid compound which uponinjection into the cavity 104 foams and polymerizes into a cellularstructure.

Applicants unique tube support sheet construction permits the use oftube receiving openings having a dimension greater than the outerdimension of the heat exchanger tubes whereby heat exchanger assembly isfacilitated while providing a tube support structure for the heatexchanger tubes operable during heat exchanger use to tightly grip theouter periphery of the heat exchanger tubes whereby vibration and sag ofthe heat exchanger tubes is obviated.

While I have shown a preferred embodiment of the invention, it will beobvious that other modifications therein may be made without departingfrom the scope of the invention as limited only by the following claims.

I claim:

1. In a structure for supporting tubes of a heat exchanger inpredetermined spaced relationship one with another, the combination of:spaced first and second members each having openings therethrough, eachof said openings in said first member being in axial alignment with acorresponding opening in said second member to thereby define pluraltube receiving passageways dimensioned to freely receive a tubetherethrough; expansible means arranged between said first and secondmembers adjacent each of said tube receiving passageways, each of saidexpansible means forming a wall portion of the tube receiving passagewayassociated therewith said expansible means comprising an elastomericmaterial which expands when exposed to heat exchange medium, saidexpansible means material being substantially unaffected by temperatureconditions of said heat exchange medium; and relatively rigid fasteningmeans for securing said first member to said second member with saidexpansible means therebetween, said fastening means encompassing theouter periphery of said expansible means and filling the space betweensaid first and second members so that on exposure of said expansiblemeans to said heat exchange medium and concurrent expansion of saidexpansible means, said expansible means wall portion tightly grips thetube in each of said passageways.

2. A structure for supporting heat exchanger tubes according to claim 1in which said first and second members comprise thermoplastic material.

3. A structure for supporting heat exchanger tubes according to claim 1in which said fastening means comprises a thermosetting resin.

4. A structure for supporting heat exchanger tubes according to claim 1in which said first and second members comprise a thermosetting resin.

5. Tube support structure as recited in claim 1, wherein said expansiblemeans comprises a ring-like element having an inner dimensionsubstantially equal to the dimension of said first and second membertube receiving openings, each of said ring-like elements being coaxialwith its associated tube opening.

6. A tube support sheet structure for use with heat exchange apparatusof the type having a plurality of heat exchanger tubes comprising afirst sheet-like member having a plurality of open-ended protrusionsterminating in a first plane spaced from said first member, each of saidprotrusions defining an opening having a dimension greater than theouter dimension of said heat exchanger tubes, a second sheet-like memberhaving a like number of openended protrusions terminating in a secondplane between said second member and said first plane, each of. saidsecond member protrusions being coaxial with one of said first memberprotrusions and defining an opening having a dimension substantiallyequal to the dimension of the opening defined by said first memberprotrusions, an element comprised of an elastomeric material whichexpands upon exposure to heat exchange medium disposed between each ofsaid first and second member protrusions and having an openingtherethrough with a dimension before exposure of said element to heatexchange medium substantially equal to the dimension of the openingdefined by said first member protrusion and coaxial therewith, saidelastomeric material being substantially unaffected by temperatu-reconditions of said heat exchange medium, and bonding means between saidfirst and second members, said bonding means encasing the outerperiphery of said expansible elements.

7. A tube support sheet according to claim 6 in which said bonding meanscomprises a thermosetting resin material.

8. A tube support sheet according to claim 7 in which said first andsecond members comprise a thermosetting resin material.

9. A tube support sheet according to claim 7 in which said first andsecond members comprise a metallic material.

10. A tube support sheet according to claim 7 in which said first andsecond members comprise a thermoplastic material.

11. A tube support sheet according to claim 7 in which each of saidexpansible elements comprise a ring-like structure having a first partincluding the inner periphery thereof in the space between said firstand second planes and a second part including the outer peripherythereof between said first member and said first plane and said secondmember and said second plane.

References Cited UNITED STATES PATENTS 2,310,927 2/1943 Bay 285--213 X2,550,560 4/1951 Heron s- 285-3824 X 2,859,948 11/1958 Callard -178 X2,989,784 6/1961 Aamodt 264263 3,088,555 5/1963 Karlgaard 188883,117,174 1/1964 Hessinger et al 264-263 3,186,294 6/1965 Williamson202173 3,187,810 6/1965 Helin et al. 165158 3,191,674 6/1965 Richardson165-458 ROBERT A. OLEARY, Primary Examiner.

FREDERICK L. MATTESON, JR., Examiner.

A. W. DAVIS, Assistant Examiner.

1. IN A STRUCTURE FOR SUPPORTING TUBES OF A HEAT EXCHANGER INPREDETERMINED SPACED RELATIONSHIP ONE WITH ANOTHER, THE COMBINATION OF:SPACED FIRST AND SECOND MEMBERS EACH HAVING OPENINGS THERETHROUGH, EACHOF SAID OPENINGS IN SAID FIRST MEMBER BEING IN AXIAL ALIGNMENT WITH ACORRESPONDING OPENING IN SAID SECOND MEMBER TO THEREBY DEFINE PLURALTUBE RECEIVING PASSAGEWAYS DIMENSIONED TO FREELY RECEIVE A TUBETHERETHROUGH; EXPANSIBLE MEANS ARRANGED BETWEEN SAID FIRST AND SECONDMEMBERS ADJACENT EACH OF SAID TUBE RECEIVING PASSAGEWAYS, EACH OF SAIDEXPANSIBLE MEANS FORMING A WALL PORTION OF THE TUBE RECEIVING PASSAGEWAYASSOCIATED THEREWITH, SAID EXPANSIBLE MEANS COMPRISING AN ELASTOMERICMATERIAL WHICH EXPANDS WHEN EXPOSED TO HEAT EXCHANGE MEDIUM, SAIDEXPANSIBLE MEANS MATERIAL BEING SUBSTANTIALLY UNAFFECTED BY TEMPERATURECONDITIONS OF SAID HEAT EXCHANGE MEDIUM; AND RELATIVELY RIGID FASTENINGMEANS FOR SECURING SAID FIRST MEMBER TO SAID SECOND MEMBER WITH SAIDEXPANSIBLE MEANS THEREBETWEEN, SAID FASTENING MEANS ENCOMPASSING THEOUTER PERIPHERY OF SAID EXPANSIBLE MEANS AND FILLING THE SPACE BETWEENSAID FIRST AND SECOND MEMBERS SO THAT ON EXPOSURE OF SAID EXPANSIBLEMEANS TO SAID HEAT EXCHANGE MEDIUM AND CONCURRENT EXPANSION OF SAIDEXPANSIBLE MEANS, SAID EXPANSIBLE MEANS WALL PORTION TIGHTLY GRIPS THETUBE IN EACH OF SAID PASSAGEWAYS.